US20170167253A1 - Apodization of Piezo-Composite Acoustic Elements - Google Patents

Apodization of Piezo-Composite Acoustic Elements Download PDF

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Publication number
US20170167253A1
US20170167253A1 US15/337,080 US201615337080A US2017167253A1 US 20170167253 A1 US20170167253 A1 US 20170167253A1 US 201615337080 A US201615337080 A US 201615337080A US 2017167253 A1 US2017167253 A1 US 2017167253A1
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thickness
piezo
composite body
transducer
insulating material
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US15/337,080
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Mikhail Lemarenko
Christoph Klieber
Andrew Hayman
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Schlumberger Technology Corp
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Schlumberger Technology Corp
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Assigned to SCHLUMBERGER TECHNOLOGY CORPORATION reassignment SCHLUMBERGER TECHNOLOGY CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HAYMAN, ANDREW JOHN, Klieber, Christoph, LEMARENKO, Mikhail
Publication of US20170167253A1 publication Critical patent/US20170167253A1/en
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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0644—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element
    • B06B1/0651—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element of circular shape
    • E21B47/0005—
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00—Survey of boreholes or wells
    • E21B47/005—Monitoring or checking of cementation quality or level
    • H01L41/047—
    • H01L41/0825—
    • H01L41/33—
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/08—Shaping or machining of piezoelectric or electrostrictive bodies
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/101—Piezoelectric or electrostrictive devices with electrical and mechanical input and output, e.g. having combined actuator and sensor parts
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/87—Electrodes or interconnections, e.g. leads or terminals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
    • G01V1/40—Seismology; Seismic or acoustic prospecting or detecting specially adapted for well-logging
    • G01V1/44—Seismology; Seismic or acoustic prospecting or detecting specially adapted for well-logging using generators and receivers in the same well

Definitions

  • This disclosure relates to improving the quality of well log data by apodization of ultrasonic elements to remove artifacts and enable simpler approximation of excitation profiles.
  • logging tools are used to determine a variety of characteristics of the well as well as making detailed records of geologic formations penetrated by the well, generally known as well logging or borehole logging.
  • Well logging is performed for the oil and gas, groundwater, mineral and geothermal exploration as well as part of environmental and geotechnical studies.
  • Some logging tools may determine characteristics of the surrounding rock formation and some logging tools may determine when cement has been properly installed in the well to achieve zonal isolation.
  • a wellbore may be targeted to produce oil and/or gas from certain zones of the geological formation.
  • the wellbore may be completed by placing a cylindrical casing into the wellbore and cementing the annulus between the casing and the wall of the wellbore. During cementing, cement may be injected into the annulus formed between the cylindrical casing and the geological formation. When the cement properly sets, fluids from one zone of the geological formation may not be able to pass through the wellbore to interact with one another. This desirable condition is referred to as “zonal isolation.” Yet well completions may not go as planned. For example, the cement may not set as planned and/or the quality of the cement may be less than expected. In other cases, the cement may unexpectedly fail to set above a certain depth due to natural fissures in the formation.
  • acoustic tools may be used for well logging. These acoustic tools may use pulse acoustic waves (e.g., sonic or ultrasonic waves) as they are moved through the wellbore to obtain acoustic evaluation data at various depths and azimuths in the wellbore.
  • the acoustic evaluation data may include not just the signal relating to characteristics of the well (e.g., quality of the cement), but also artifacts of the tool and other sources.
  • the generation and transmission of the ultrasonic waves may show a pattern of lobes at various directions, including a main (central) lobe and other lobes to the side of the main lobe, called side lobes.
  • a transducer configured to emit or receive an acoustic signal includes a front electrode, and a central layer behind the front electrode.
  • the central layer has a substantially constant first thickness from a central point to an edge of the central layer.
  • the central layer includes a piezo-composite body having a second thickness within the first thickness, wherein the second thickness of the piezo-composite body varies from the central point to the edge.
  • the central layer also includes an insulating material having a third thickness, wherein the third thickness of the insulating material varies from the central point to the edge in an opposite manner to the second thickness.
  • the first thickness is equal to the second thickness plus the third thickness.
  • the transducer also includes a back electrode behind the central layer, having a back face coupled to a backing material. Variations in the second thickness of the piezo-composite body and the third thickness of the insulating material from the central point to the edge cause the piezo-composite body to cause reduced side lobes in comparison to a different transducer with another piezo-composite body having the disk-like geometry but a single thickness that does not vary from the central point to the edge.
  • a method for making a transducer configured to reduce side lobes includes providing a central layer between a front electrode and a back electrode of the transducer, wherein the central layer has a substantially constant first thickness throughout.
  • the central layer includes a piezo-composite body having a second thickness along an axial direction, and a width along a radial direction towards an radial edge, and an insulating material having a third thickness.
  • the method for making a transducer configured to reduce side lobes also includes varying the second thickness of the piezo-composite body to differ in various locations along the radial direction towards the radial edge.
  • the method for making a transducer configured to reduce side lobes further includes varying the third thickness of the insulating material such that the first thickness of the central layer comprises the third thickness of the insulating material combined with the second thickness of the piezo-composite body.
  • a downhole tool includes a rotating measurement component configured to rotate to obtain measurements at a plurality of azimuthal angles in a well, wherein the rotating measurement component includes one or more transducers configured to emit acoustic signals at each of the plurality of azimuthal angles in the well and detect acoustic return waveforms that result when the emitted acoustic signals interact with the well.
  • Each of the one or more ultrasonic transducers includes a front, and a central layer behind the front electrode. The central layer has a substantially constant thickness throughout and includes a piezo-composite body and an insulating material.
  • Each of the one or more ultrasonic transducers also includes a back electrode behind the central layer, having a back face configured to be coupled to a backing material.
  • FIG. 1 is a schematic of a system for obtaining well logging data with reduced artifacts, in accordance with an embodiment
  • FIG. 2 is a schematic of an acoustic downhole tool that may be used to obtain the well logging data, in accordance with an embodiment
  • FIG. 3A illustrates an excitation profile of a non-apodized ultrasonic transducer in comparison to a Gaussian profile, in accordance with an embodiment
  • FIG. 3B illustrates a pattern of a pressure field perpendicular to a front face of a non-apodized ultrasonic transducer at a location that is far from the non-apodized ultrasonic transducer in comparison to a Gaussian profile, in accordance with an embodiment
  • FIG. 4 is a cross-sectional view of an apodized piezo-composite ultrasonic transducer, in accordance with an embodiment
  • FIG. 5 illustrates the effectiveness of apodizing the transducer to a given fraction of its full response, in accordance with an embodiment
  • FIG. 6 illustrates a piezo-composite body including an active piezoelectric material element and grooves filled with an insulating material, in accordance with an embodiment
  • FIG. 7 illustrates a piezo-composite body including an active piezoelectric material element and a tapered region filled with an insulating material, in accordance with an embodiment
  • FIG. 8 illustrates a piezo-composite body including an active piezoelectric material element and a tapered region filled with different insulating materials which further divide the tapered region into sub-regions, in accordance with an embodiment
  • FIG. 9 illustrates a piezo-composite body including an active piezoelectric material element and strips filled with an insulating material, in accordance with an embodiment
  • FIG. 10 illustrates a top view of a piezo-composite body and irregularly shaped regions filled with an insulating material, in accordance with an embodiment.
  • FIG. 1 illustrates a system 10 for obtaining well logging data with reduced artifacts using a downhole tool (e.g., an acoustic logging tool).
  • a downhole tool e.g., an acoustic logging tool
  • FIG. 1 illustrates surface equipment 12 above a geological formation 14 .
  • a drilling operation has previously been carried out to drill a wellbore 16 .
  • an annular fill 18 e.g., cement
  • an annulus 20 the space between the wellbore 16 and casing joints 22 and collars 24 —with cementing operations.
  • casing joints 22 are coupled together by the casing collars 24 to stabilize the wellbore 16 .
  • the casing joints 22 represent lengths of pipe, which may be formed from steel or similar materials.
  • the casing joints 22 each may be approximately 13 m or 40 ft long, and may include an externally threaded (male thread form) connection at each end.
  • a corresponding internally threaded (female thread form) connection in the casing collars 24 may connect two nearby casing joints 22 . Coupled in this way, the casing joints 22 may be assembled to form a casing string to a suitable length and specification for the wellbore 16 .
  • the casing joints 22 and/or collars 24 may be made of carbon steel, stainless steel, or other suitable materials to withstand a variety of forces, such as collapse, burst, and tensile failure, as well as chemically aggressive fluid.
  • the surface equipment 12 may carry out various well logging operations to detect conditions of the wellbore 16 .
  • the well logging operations may measure parameters of the geological formation 14 (e.g., resistivity or porosity) and/or the wellbore 16 (e.g., temperature, pressure, fluid type, or fluid flowrate).
  • Other measurements may provide acoustic evaluation data (e.g., flexural attenuation and/or acoustic impedance) that may be used to verify the cement installation and the zonal isolation of the wellbore 16 .
  • One or more acoustic logging tools 26 may obtain some of these measurements.
  • FIG. 1 shows the acoustic logging tool 26 being conveyed through the wellbore 16 by a cable 28 .
  • a cable 28 may be a mechanical cable, mechanical cable attached to an electrical cable, or an electro-optical cable that includes a fiber line protected against the harsh environment of the wellbore 16 .
  • the acoustic logging tool 26 may be conveyed using any other suitable conveyance, such as coiled tubing.
  • the acoustic logging tool 26 may be, for example, an UltraSonic Imager (USI) tool and/or an Isolation Scanner (IS) tool by Schlumberger Technology Corporation.
  • USI UltraSonic Imager
  • IS Isolation Scanner
  • the acoustic logging tool 26 may obtain measurements of acoustic impedance from ultrasonic waves and/or flexural attenuation. For instance, the acoustic logging tool 26 may obtain a pulse echo measurement that exploits the thickness mode (e.g., in the manner of an ultrasonic imaging tool) or may perform a pitch-catch measurement that exploits the flexural mode (e.g., in the manner of an IS tool). These measurements may be used as acoustic evaluation data to identify likely locations where solid, liquid, or gas is located in the annulus 20 behind the casing 22 .
  • the acoustic logging tool 26 may be deployed inside the wellbore 16 by the surface equipment 12 , which may include a vehicle 30 and a deploying system such as a drilling rig 32 . Data related to the geological formation 14 or the wellbore 16 gathered by the acoustic logging tool 26 may be transmitted to the surface, and/or stored in the acoustic logging tool 26 for later processing and analysis.
  • the vehicle 30 may be fitted with or may communicate with a computer and software to perform data collection and analysis.
  • FIG. 1 also schematically illustrates a magnified view of a portion of the cased wellbore 16 .
  • the acoustic logging tool 26 may obtain acoustic evaluation data relating to the presence of solids, liquids, or gases behind the casing 22 .
  • the acoustic logging tool 26 may obtain measures of acoustic impedance and/or flexural attenuation, which may be used to determine where the material behind the casing 22 is a solid (e.g., properly set cement) or is not solid (e.g., is a liquid or a gas).
  • the surface equipment 12 may pass the measurements as acoustic evaluation data 36 to a data processing system 38 that includes a processor 40 , memory 42 , storage 44 , and/or a display 46 .
  • the acoustic cement evaluation data 36 may be processed by a similar data processing system 38 at any other suitable location.
  • the data processing system 38 may collect the acoustic evaluation data 36 , remove unwanted noises and artifacts, and determine whether such data 36 represents a solid, liquid, or gas using any suitable processing (e.g., T 3 processing, Traitement réelle Tôt , or Very Early Processing).
  • the processor 40 may execute instructions stored in the memory 42 and/or storage 44 .
  • the memory 42 and/or the storage 44 of the data processing system 38 may be any suitable article of manufacture that can store the instructions.
  • the memory 42 and/or the storage 44 may be ROM memory, random-access memory (RAM), flash memory, an optical storage medium, or a hard disk drive, to name a few examples.
  • the display 46 may be any suitable electronic display that can display the logs and/or other information relating to classifying the material in the annulus 20 behind the casing 22 .
  • the acoustic evaluation data 36 from the acoustic logging tool 26 may be used to determine whether cement of the annular fill 18 has been installed as expected.
  • the acoustic evaluation data 36 may indicate that the cement of the annular fill 18 has a generally solid character (e.g., as indicated at numeral 48 ) and therefore has properly set.
  • the acoustic evaluation data 36 may indicate the potential absence of cement or that the annular fill 18 has a generally liquid or gas character (e.g., as indicated at numeral 50 ), which may imply that the cement of the annular fill 18 has not properly set.
  • the annular fill 18 has the generally liquid character as indicated at numeral 50 , this may imply that the cement is either absent or was of the wrong type or consistency, and/or that fluid channels have formed in the cement of the annular fill 18 .
  • ascertaining the character of the annular fill 18 may be more accurate and/or precise than comparable processing when the noises and artifacts remains in the acoustic evaluation data 36 .
  • FIG. 2 provides an example of the operation of the acoustic logging tool 26 in the wellbore 16 .
  • an ultrasonic transducer 52 in the acoustic logging tool 26 may emit acoustic waves 54 out toward the casing 22 .
  • Reflected waves 56 , 58 , and 60 may correspond to acoustic interactions with the casing 22 , the annular fill 18 , and/or the geological formation 14 or an outer casing.
  • the reflected waves 56 , 58 , and 60 may vary depending on whether the annular fill 18 is of the generally solid character 48 or the generally liquid or gas character 50 .
  • the acoustic logging tool 26 may use any suitable number of different techniques, including measurements in a pulse-echo geometry and/or flexural attenuation, to name a few.
  • the acoustic evaluation data 36 may contain unwanted noise and artifacts such as side lobes in the transducer radiation pattern. Side lobes are caused by sound energy that spreads out from the transducer at angles other than the primary path.
  • the ultrasound beam structure emitted off axis may interfere with the main contribution or itself, which leads to unwanted artifacts and is difficult to model mathematically.
  • Shaping of the excitation profile of an ultrasonic transducer may be done by shaping the emission profile, for example by disabling certain areas of the transducer through shaping or patterning the electrodes of the ultrasonic transducer. Ideally, this structure is sub-wavelength (i.e. smaller) than the ultrasonic wavelength of interest.
  • the ultrasonic transducer is protected with a front face made of electrically conductive materials, whereas the conductivity of the front face rules out the use of shaped/patterned electrodes.
  • alternative approaches are taken to taper the transducer excitation towards the edges of the aperture in order to reduce side lobes and shape the excitation profile to better match simple mathematical models.
  • Simpler mathematical models may be easier to implement in computing code and may save significant computational time for the data processing system 38 .
  • one example of the disclosure involves altering the emission profile of the transducer to shape the excitation profile.
  • the apodized excitation profile may approximate a mathematical model (e.g., a Gaussian profile and/or any other suitable profile).
  • FIG. 3A shows an example of an excitation profile 70 of a non-apodized ultrasonic transducer, in comparison to a Gaussian profile 72 .
  • the excitation profile 70 exhibits an abrupt transition at the edges of the piezo-electrically active area (e.g., distance perpendicular to axis (across transducer face) is zero) and departs sharply from the Gaussian profile 72 .
  • FIG. 3B shows an example of a pressure field pattern 74 of a non-apodized ultrasonic transducer at a location that is far from the non-apodized ultrasonic transducer, in comparison to a Gaussian profile 76 .
  • the profile 74 has side lobes while the Gaussian profile 76 is nearly flat.
  • the tapering of the amplitude of the side lobes and shaping the excitation profile to better match simple mathematical models may enable optimizing computation time in signal analyzing and processing (e.g., the use for fast and lightweight simulations of ultrasonic wave propagation).
  • FIG. 4 shows a cross sectional view of an apodized ultrasonic pulse-echo transducer 80 with a disk-like geometry (e.g., a disk-like geometry having a circular shape, an elliptical shape or any other suitable shapes).
  • the transducer 80 includes electrodes on both front and back faces: a front electrode 84 on a front face and a back electrode 90 on a back face.
  • the front face is protected by a front layer 82 which may also serve as or can be a front electrode if it is electrically conductive.
  • the back face is coupled to a backing material 92 that serves the dual functions of damping the vibrations of a piezoelectric material element 88 and attenuating the waves transmitted backwards into the backing.
  • an insulating material element 86 is introduced between the front of the piezoelectric material element 88 and the front electrode 84 .
  • the layer of the insulating material element 86 may be thicker towards the edge of the transducer in order to taper the response off towards the edge. In another embodiment, the thickness of the insulating material element 86 may be approximately 5% or less than 5% of the thickness of piezoelectric material element 88 .
  • the piezoelectric material element 88 is matched to accommodate the insulating material element 86 and leaves the front layer 82 and the front electrode 84 flat (e.g., without shaping/patterning of the front layer 82 and front electrode 84 ).
  • the insulating material element 86 is a dielectric material with a much lower permittivity than that of the piezoelectric material.
  • such an ultrasonic transducer includes a piezoelectric material or a piezo-composite active element including piezoelectric rods in an epoxy matrix, an epoxy insulation layer, a front electrode, a front face made of stainless steel, titanium or a gas-proof elastomer such as Chemraz® Perfluoelastomer and finally a backing material.
  • the thickness of the insulating material element may have direct impacts on the effectiveness in tapering off the response; as illustrated is the epoxy thickness required to apodize the transducer to a given fraction of its full response.
  • the profile 102 is obtained based on a normalized output versus epoxy thickness for a 2.5 mm thick piezo-composite, assuming relative permittivities of 600 for the piezo-composite and 5 for the epoxy insulator and a piezo-composite thickness of 2.5 mm.
  • a high-permittivity filler e.g., ceramic powder
  • the present disclosure aims to apodize the emission and/or reception profile of piezo-composite elements used in ultrasonic transducers. This may be achieved by disabling certain areas of the piezoelectric layer through milling and refilling with epoxy or other insulating materials of low permittivities. Such an approach circumvents a potential limitation of transducers having a conductive front face, which may not allow the deposition of a certain electrode pattern. The more abrupt the change of the initial pressure profile is at the edges of the active element, the more pronounce the side lobe pattern will be. A Gaussian like pressure profile may be desirable for the aforementioned reasons.
  • the active piezoelectric layer 118 includes at least one axial centric groove 120 filled with an insulating material such as epoxy.
  • an insulating material such as epoxy.
  • a high-permittivity filler such as ceramic powder may also be included in the epoxy to allow the use of a thicker insulating layer that is easier to manufacture.
  • the groove/grooves 120 may be directly under the electrode 116 closer to the front (or on the back side), and the orientation and dimensions of the grooves 120 are symmetrical in directions towards the edge.
  • the orientation and dimensions of the grooves 120 may be asymmetrical towards the edge.
  • each of the grooves 120 has a width w and a thickness t 1
  • the active piezoelectric layer 118 has a thickness t 2 .
  • a distance between adjacent grooves 120 may vary (e.g., the spacing of the grooves 120 may vary).
  • the thickness ti of the grooves 120 may be the same as the thickness t 2 of the active piezoelectric layer 118 .
  • the thickness t 1 of the grooves 120 may be thin (e.g., less than 30% of the thickness t 2 of the active piezoelectric layer 118 ).
  • the grooves 120 may each have a different thickness t 1 , and the thickness ratio t 1 /t 2 may vary in the direction towards the edge.
  • the grooves 120 that are closer to the edge may have greater thickness ratios t 1 /t 2 than the grooves 120 that are farther away from the edge (e.g., closer towards the center of the disk-like transducer in the radial direction).
  • the grooves 120 may also each have a different width w, and value of w may vary in the direction towards the edge. For example, the grooves 120 that are closer to the edge may have greater w values than the grooves 120 that are farther away from the edge.
  • the above mentioned embodiments by itself or in combination thereof are aimed to apodize the emission/reception profile of piezo-composite elements to be a nearly Gaussian profile.
  • FIG. 7 a layer of piezo-composite material according to one embodiment of the present disclosure is shown in a top view 142 and a cross-sectional view 144 .
  • the active piezoelectric layer 148 is tapered in its end region towards the edge, wherein the tapered region is filled with an insulating material of low permittivity such as epoxy. For the reason as set forth above, a high-permittivity filler such as ceramic powder may be included in the epoxy.
  • the insulating material filled layer 150 may be directly under the electrode 146 closer to the front (or back), and the orientation and dimensions of the insulating material filled layer 150 is symmetrical in directions towards the edge.
  • the insulating material filled layer 150 has a width w and a thickness t 1 , and the active piezoelectric layer 148 has a thickness t 2 .
  • the outline 156 of the boundary between elements 148 and 150 may vary.
  • the thickness t 1 of the insulating material filled layer 150 may be between 0% and 5% of the thickness t 2 of the active piezoelectric layer 148 .
  • the thickness t 1 may be a constant value or it may vary in the direction toward the edge. In general, the thickness t 1 may be big enough to be mostly or fully electrically insulating. And for the tapering approach, the relative thickness of the layer may be calculated without much impact of the piezo-disc thickness.
  • the insulating material filled layer 150 may have varying thickness t 2 in directions towards the edge (e.g., varying t 1 /t 2 ratio as a function of width w), and the t 1 /t 2 ratio may increase towards the edge.
  • the varying t 1 /t 2 ratio as a function of width w may also be achieved via steps rather than a smooth curve.
  • a layer of piezo-composite material is shown in a top view 172 and a cross-sectional view 174 .
  • the active piezoelectric layer 178 is tapered in its end region towards the edge, wherein the tapered region is filled with different insulating materials, which further divide the tapered region as shown by numeral 183 .
  • the insulating layer 180 may include more than one materially different sub-regions having the same or different widths (w 1 , w 2 , and w 3 , etc.) but the same thickness ti.
  • One example of the materially different sub-regions may be sub-region 184 , 186 and 188 each is made of a different type of epoxy resin.
  • sub-region 184 , 186 and 188 each is made of the same type of epoxy, but such epoxy contains different amounts of fillers (e.g., high-permittivity ceramic powders).
  • fillers e.g., high-permittivity ceramic powders.
  • the active piezoelectric layer 208 includes at least one strip 210 , planarly extending across the piezoelectric layer 208 (e.g., planarly extending from one edge to the other) and filled with an insulating material such as epoxy.
  • an insulating material such as epoxy.
  • not all of the strips 210 are extending across the piezoelectric layer 208 (e.g., the strips 210 may planarly extend through only a portion of the piezoelectric layer 208 , but not all the way across the piezoelectric layer).
  • a high-permittivity filler such as ceramic powder may also be included in the epoxy to allow the use of a thicker insulating layer that is easier to manufacture.
  • the strip/strips 210 may be directly under the electrode 206 closer to the front (or on the back side), and the orientation and dimensions of the strips 210 are symmetrical in directions towards the edge. In another example, the orientation and dimensions of the strips 210 may be asymmetrical towards the edge. In one example, each of the strips 210 has a width w and a thickness t 1 , and the active piezoelectric layer 208 has a thickness t 2 . These are dimensions that may be adjusted to reduce side lobes and achieve a more Gaussian like emission/reception profile.
  • the thickness t 1 of the strips 210 may be the same as the thickness t 2 of the active piezoelectric layer 208 . In another example, the thickness t 1 of the strips 210 may be thin (e.g., less than 30% of the thickness t 2 of the active piezoelectric layer 208 ). In another example, the strips 210 may each have a different thickness t 1 , and the thickness ratio t 1 /t 2 may vary in the direction towards the edge. Furthermore, the strips 210 that are closer to the edge may have greater thickness ratios t 1 /t 2 than the strips 210 that are farther away from the edge (e.g., closer towards the center of the disk-like transducer in the radial direction).
  • the strips 210 may also each have a different width w, and value of w may vary in the direction towards the edge. For example, the strips 210 that are closer to the edge may have greater w values than the strips that are farther away from the edge.
  • the above mentioned embodiments by itself or in combination thereof are aimed to apodize the emission/reception profile of piezo-composite elements to be a nearly Gaussian profile.
  • the active piezoelectric layer 232 includes at least one irregularly shaped region 234 filled with an insulating material such as epoxy.
  • the piezo-composite material may have a disk like geometry having an elliptical shape as shown or any other irregular or regular shapes suitable.
  • the orientation and dimension of the random shaped region 234 may be symmetrical or asymmetrical towards the edge.
  • the irregularly shaped region has a thickness t 1 (not shown), and the active piezoelectric layer 232 has a thickness t 2 (not shown).
  • the thickness t 1 of the irregularly shaped regions 234 may be the same as the thickness t 2 of the active piezoelectric layer 232 . In another example, the thickness t 1 of the irregularly shaped regions 234 may be thin (e.g., less than 30% of the thickness t 2 of the active piezoelectric layer 232 ). In another example, the irregularly shaped regions 234 may each have a different thickness t 1 , and the thickness ratio t 1 /t 2 within the irregularly shaped regions 234 may vary in the direction towards the edge.
  • the thickness ratio t 1 /t 2 within the irregularly shaped regions 234 may increase (e.g., greater t 1 /t 2 value) towards the edge.

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  • Geophysics (AREA)
  • Manufacturing & Machinery (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
US15/337,080 2015-12-15 2016-10-28 Apodization of Piezo-Composite Acoustic Elements Abandoned US20170167253A1 (en)

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EP15290312.6A EP3181246A1 (de) 2015-12-15 2015-12-15 Apodisierung von akustischen piezo-verbundelementen
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110886604A (zh) * 2019-12-02 2020-03-17 中国石油大学(华东) 一种基于计算机模拟技术的高效地热资源勘察方法
CN111742243A (zh) * 2018-02-08 2020-10-02 斯伦贝谢技术有限公司 用于测量地层速度的超声换能器
US11808143B2 (en) 2018-05-14 2023-11-07 Schlumberger Technology Corporation Methods and apparatus to measure formation features
US11921249B2 (en) 2018-02-08 2024-03-05 Schlumberger Technology Corporation Ultrasonic acoustic sensors for measuring formation velocities

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FR2646513B1 (fr) 1989-04-26 1991-09-20 Schlumberger Prospection Procede et dispositif de diagraphie pour l'inspection acoustique d'un sondage muni d'un tubage
US5553035A (en) * 1993-06-15 1996-09-03 Hewlett-Packard Company Method of forming integral transducer and impedance matching layers
US5706820A (en) * 1995-06-07 1998-01-13 Acuson Corporation Ultrasonic transducer with reduced elevation sidelobes and method for the manufacture thereof
US5657295A (en) * 1995-11-29 1997-08-12 Acuson Corporation Ultrasonic transducer with adjustable elevational aperture and methods for using same
US7036363B2 (en) * 2003-07-03 2006-05-02 Pathfinder Energy Services, Inc. Acoustic sensor for downhole measurement tool

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111742243A (zh) * 2018-02-08 2020-10-02 斯伦贝谢技术有限公司 用于测量地层速度的超声换能器
US11921249B2 (en) 2018-02-08 2024-03-05 Schlumberger Technology Corporation Ultrasonic acoustic sensors for measuring formation velocities
US11808143B2 (en) 2018-05-14 2023-11-07 Schlumberger Technology Corporation Methods and apparatus to measure formation features
CN110886604A (zh) * 2019-12-02 2020-03-17 中国石油大学(华东) 一种基于计算机模拟技术的高效地热资源勘察方法

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